The MLB schedule is almost entirely comprised of 3-game series with a few exceptions in 2- and 4-game series. Two advantages of a short series are:
- Increased variety in the schedule;
- Game three always has some "meaning" (2-0 you can sweep, 1-1 you're playing for the series, 0-2 you're avoiding the sweep).
Quality of opponent isn't much of a concern for an elite team, they have a chance to win every day, or an awful team, which has little chance of winning on any day, but not having to face a top team for more than 3 games can help keep losing streaks short and fan interest from waning. At least this is what I understand to be an element of the reasoning behind a short series, with #1 and #2 being the major advantages. Having multiple series against a particular team gives both teams an opportunity to change via trade, injury, or call-up, and make the subsequent series a fresh experience for the teams and the fans.
However, there is a major disadvantage with the 3-game series: Teams do not face the entire rotation. This leads to teams facing 1-2-3 with their 3-4-5, which greatly reduces their ability to win. Sometimes rotations match up, but whenever they don't one team theoretically has an advantage (not accounting for the quality of the rotation). If every team faced the full rotation in a series then team records would more accurately reflect a team's true talent level. If every teams' rotation face each other in order (your #1 vs. their #1 and so on) during a series then records would become even more representative of true talent. With the volatility of pitchers though, it is unclear how much scheduling would be able to facilitate being able to face rotations in order.
The simplest and most consistent implementation of this schedule would have a series play out over one week, with Monday as the travel day and one day during the week as a day off. If the league does not wish to have any days without at least one game being played then they can alternate the travel day between Monday and Tuesday and the day off between Thursday and Friday. The main advantage of a 7-day schedule is far less travel for the players and teams. It's less strenuous on the players and less expensive for the teams. A 3-game series ends and is displaced by the next series so quickly that the schedule, and MLB coverage lacks focus. Seeing each team's entire rotation over the course of a week also allows fans and media to focus on one team. Team can more easily promote a series against marquee teams like the Yankees if they're going to be in town for 5 games and will definitely play on the weekend. There is also a greater significance to the outcome of longer series, especially a division series. Ideally, teams would prepare for each series as they would a playoff series, with their best pitcher facing their opponent's best pitcher and so on.
There are disadvantages to the 5-game, 7 day series (the 5/7). The largest disadvantage is that, unless the season is extended, teams will only play 125 games. As the season is currently 162 games over approximately 180 days with 18 days off, leaving 37 games unaccounted for. With 25 weeks plus 5 days in the season, the 5/7 has 2 days off per week for 50 days off. These extra 32 days off can be used in two ways: abandon the strict weekly formula and structure the schedule much as it is today except with 5-game series, or squeeze more games into the weekly format with double headers and fewer days off per week. The biggest advantage of the 5-game series is facing the full rotation, with the added benefits of guaranteed weekend games and increased focus on the opponent. Both solutions to making up the missing 17 games lose the benefit of facing the rotation in order, as teams will get out of sync once as they play series over 5 games. Perhaps it would be possible to structure the schedule in a way that all teams would play 6- or 7-game series at the same time. There's actually another benefit to maintaining the weekly format but adding 6- and 7- game series to the standard 5: divisional games. Slightly longer series allows for more games against divisional opponents while lessening the more severe bias toward divisional opponents in the current schedule. While this would mean fewer divisional games, a 6 or seven game series against a divisional opponent late in the season would have far more significance than a 3-game series. Several series late in the season would play more like a postseason series because of their significance. Counting the final 5 days of the season as compressed week (or simply extending the season by 2 days), 26 weeks, twelve 7-game series and eight 6-game series or ten 7s and 12 6s and four 5s. I hadn't done the math until now, but this looks more like a system based on the 7-game series than a 5-game series, but either still guarantees each team faces the entire rotation. Alternatively teams could play fifteen 7-game series and eleven 5-game series.
It takes significantly more adaptation to adjust the schedule to a weekly series format, and perhaps more benefit will be realized by constructing the schedule conventionally with 5-game series and one 7-game or two 6-game series to fill out the schedule to 162 games. I realize that the league has made no indication that they have any intention of modifying the 3-game series format, but I like the 5-game series format and wanted to open the discussion on the merits of the concept.